<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<center>
  <h1>账号已存在</h1>
  <p>点击重新返回<a href="reg.html">注册</a> 页面,或是返回 <a href="index.html">主页</a></p>
</center>
</body>
</html>